Work-clamping mechanism for sewing machines



E. ALLEN WORK CLAMPING MECHANISM FOR SEWING MACHINES Filed April 13. 1926 4 Sheets-Sheet 1 INES Y E N R O T 1m, h5g5 E. B. ALLEN WO RK CLAMPING MECHANISM FOR SEWING MACHINES Filed April 13, 1926 4 Sheets-Sheet 2 INVENTOR WITNESSES i BY W &

7 ATTORNEY @m'29, 192?. E, "ii 33L E. B. ALLEN woax CLAMPING mzcumism FOR sawme mcamas Filed April 13. 1926 4 Sheets-Sheet 3 INVENTOR E. B. ALLEN WORK CLAMPING MECHANISM FOR SEWING MACHINES Filed April 13, 1926 4 Sheets-Sheet 4 INVENTOR Patented Not. 29, T921 Iii. r on t n .1

EDWARD B. ALLEN, CF NEWTOWN, CONNECTICUT, ASSIGNCR TO THE SINGER MANU- FACTURING'COMPANY, 01E ELIZABETH, NEW JERSEY, A. CCRPCRATICN CE NEW a teaser.

- Application filed April 13, 1926. serial No. 101,662.

This invention relates to sewing machines more particularly of the type having relatively movable stitch-forming and work clamping devices and adapted to sew a group of stitches and then come to rest. Machines of this type commonly have a needle-throat member, and the workclamp includes upper and lower clamping means, oi which the lower has an opening for the needle-throat member permitting the work-clamp and needle-throat member to be relatively shitted, not only during the sewing, but also out of and into sewing relation. Tn a sewing machine of the buttonhole type, for example,

' the work-clamp and needle-throat member are shifted out of sewing relation to allow the buttonhole cutter to act upon the work. The needle-throat opening or clearance slot customarily provided in the lower workclamping means to permit the needle-throat member and work-clamp to be shifted out of sewing relation constitutes a gap in the lower clamping means preventing clamping otthe work on all sides or all around the area exposed by the work-clamp to the action of the stitch-forming mechanism. Hence there is liability that the work will be pulled and distorted by the" action of the stitch-forming mechanism, particularly when sewing adjacent the gap on the side of the stitched figure where the work is not clamped.

The present invention therefore has for an object to provide, in a machine of the class described, for the clamping of the work "on all sides or substantially all around the area exposed to the action otthe stitchtorming mechanism, without blocking the relative movement of the work-clamp and needle-throat member out of and into sewing relation. 7,

To this end there are provided auxiliary lower clamping means arranged to fill the gap in the Lefie'ctive work-clamping portions of the lower clamping means occasioned by said auxiliarylower clamping means being displaceable from work-clamping position so as not to block relative movement of the work-clam and needle-throat member be tween sewing periods. Preferably the auxiliary lower clamping means are in the form or" one or more levers pivotally supported on the needle-throat clearance slot,

the main-lower clamping means or plates, so i point taken longitudinally of the machine bed and showing the work-clamp and needlethroat member moved out of sewing relation. Fig. 3 isa similar view of the parts after sewing relation thereof is restored. Fig. 4 is a bottom plan view of the upper work-clamping feet. Fig. 5 is a plan view of the lower work-clamping means and needle-throat member in sewing relation. Fig. 6 is a similar view of these parts out of sewing relation. Fig. 7 is a sectional U view on the line 7- 7, Fig. 5. Fig. 8 is a plan view of a modified form of the inventionwith the parts in sewing relation. Fig. 9 is a similar view with the parts out of sewing relation, and F ig. 10 is a fragmentary vertical section of the parts in the-position shown in Fig. 9.

Thisinvention is shown as embodied in a sewing machine of the buttonhole type designed tor sewing circular eyelets and constructed substantially in accordance with the disclosure of m Patent No. 1,34=6,102, of July 13, 1920. uch a machine is constructed with a frame including the hollow rec-- tangular bed 1, standard 2 and overhanging arm 3 terminating in the head 4:. The stitchlorming mechanism is of the type employing an upper straight reciprocating depthstitch needle 5- and a lower curved slit-stitch needle 6 with suitable driving mechanism such as disclosed in my Patent No. 1,162,-

207, of Nov. 30, 1915. The lower needle 6 is carried by the usual rotary turret 7.

The work-clamp comprises the usual lower clamping plates 8, 8, and upper clamping feet 9, 9; the feet 9 being carried by the clamping arms 10 fulcrumed at 11 on blocks, one of which is shown at 12, mounted on the lower clamping plates 8. The clamps are closed by depression of an arm 13 fixed to the rock-shaft section 14 having a cam-mom ber 15 which depresses the upper clamp-arm .10 to force the corresponding foot 9 into clamping engagement with the work. A work-clamp of this nature is disclosed, for example, in my Patent No. 1,37 9,894, of May 31, 1921. The work-clamp is moved over the bed 1 during the sewing by the usual connections with the feed-wheel 16. Turning movements are also imparted to the turret 7 and needle-bar 5 by the usual connections with the feed-wheel 16. I

The buttonhole cutting mechanism is constructed substantiall in accordance with the disclosure of my atent No. 1,048,786, of Dec. 31, 1912, and comprises the buttonhole cutter-levers 17, 18, fulcrumed at 19 on the travelling fulcrum-block 20. The tails of the cutter-levers 17, 18, are engaged by the cutter closing cams 21, 22, on the cuttershaft 23 which in the present machine is given a single rotation prior to sewing by means of the usual one-rotation clutch device. The cutter-fulcrum block 20 has travelling movements imparted to it by the usual link connection 24 having a follower 25 entering the cutter advancing and retracting cam 26 on the cutter-shaft 23. The cutterlever 18 carries the round eye cutter 27 which coacts with the fiat brass or anvil 28 on the lever 17. The period of action of the stitch-forming mechanism is controlled by the usual stop-motion device 29 which establishes and interrupts driving relation between the constantly running pulley 30 and the sewing shaft 31.

The sewing needles 5 and 6 are both reciprocated to pass loops of thread through or across the plane of the work. These needles pass through the crescent-shaped aperture 32 in the usual needle-throat memmember 33 which is normally in engagement with the under surface of the work. Fig. 3, exposed by the aperture 34 in the lower clamp-plates 8. The upper clamping feet are apertured at 35, Fig. 4, to expose an area of the upper surface of the work to the action of the stitch-forming mechanism. The aperture 34 in the lower clamp-plates thus permits the needle-throat member to engage the work and support the work against the thrust of the upper needle 5.

During the buttonhole cutting operation the needle-throat member 33 must be gotten out of the way of the anvil member 28. To this end it is mounted on a lever v36 fulcrumed at 37 on the turret 7. When the cutter-levers are advanced to cutting position an arm 38 on the lower cutter-lever 17 engages the shank of the needle-throat member 33 and tilts the lever 36 forwardly. as shown in Fig. 2, thus displacing the needlethroat member 33 from the aperture 34 in the lower clamp-plates longitudinally of the needle-throat clearance slot 39 in such clampplates. This tilting throat-plate expedient is the work in this opening to support the work against the pressure of the upper clamping feet. Hence there has been a tendency for the work to draw inwardly and become distorted in the vicinity of this gap or unclamped portion.

According to the embodiment of the present improvement illustrated in Figs. 1 to 7, inclusive, an auxiliary lower work-clamping element 40 is disposed in the opening or slot 34 in work-clamping relation with the upper clamping feet 9, when the needlethroat member 33 and work clamp are in sewing relation, Fig. 3. The auxiliary lower work-clamping element 40 is formed as the L-shaped end of a lever 41 fulcrumed at 42 in a depression in one of the lower clampplates 8, Figs. 5 and 6, the tail of the lever 41 being acted upon by the spring 43 to yieldingly urge the clamping element 40 to work-clamping position, Fig. 5, with the pin 44 depending from the element 40 resting against the front edge of the needle-throat member 33.

When the cutter-levers are shifted forwardly preparatory to cutting the buttonhole or eyelet-hole. the needle-throat member 33 which is shifted along the slot 39 pushes against the pin 44 and displaces the auxiliary clamping member 40 longitudinal- 1y of such slot to the position shown in Figs. 2 and 6. \Vhen the cutter-levers are retracted, the spring 43 restores the auxiliary clamping member 40 to work-clamping position, Figs. 3 and Thus the area of the work exposed to the action of the stitchforming mechanism is securely clamped on all sides and distortion of the stitched figure is prevented.

According to the modified embodiment of the invention illustrated in Figs. 8, 9 and 10, the needle-throat clearance opening or slot 39 has been widened considerably at 39, 39' to receive the work-clamping extremities 45, of a pair of auxiliary lower work-clamping elements in the form of levers 4G, pivoted at 47 on the respective lower clamp-plates 8. Springs 48 serve to yieldingly hold the levers 46 in work-clamping position, Fig. 8. Stop pins 49 in the respective lower clamp-plates 8 adjacent their meeting edges limit the motion of the leversdfi under the influence of the springs 48. The meeting corners of the working ends of the leversefi are beveled off or slanted at so as to meet the semicircular needle-throat working clearance 51 in the lower clamp-plates S and form a complete lower work-clam ing surface on all sides or all around the sewing position of the needle-throat member 33. When'the workclamp and needle-throat member are relatively shifted out of sewing relation, as when i during the -advance of the cutter-levers preparatory to cutting the buttonhole. The lower cutter-lever 17 has mounted on the side thereof a roll 17 which rides over the hump 17 on the lever 17 pivoted at 17 on the standard 2 and depresses such lever causing its downwardly curved free endl7 to depress the lever 13 previously described.

This mechanism is substantially the same as that described in my said 1,379,894. v p

The invention is not to be understood as limited to the particular type of sewing machine shown and described or to the particular details of construction and arrangement of parts in the embodiments disclosed. So far as I am aware I am the first to provide a sewing machine with a work-clamp having upper and lower clamping means for clamping the work all around the area exposed to the action of the stitch-forming mechanism with provision for relatively Patent No.

shifting out of and into sewing relation the work-clamp and an element which operates in the work-exposing aperture of a clam ing element of the work-clamp during tie sewing. A thin cover-plate 45 is preferably provided to cover all of the lever 41 except the work clamping extremity thereof. Suitable thin sheet metal covers 45 are preferably used to cover the springs 48 and the shanks of the levers 46, the working extremities 45 being exposed.

Having thus set forth the nature. of the invention, what I claim herein is:

1. A sewing machine having, in combina-- tion, stitch-forming mechanism, a workclamp including co-acting upperand lower work-clamping means apertured to expose an area of the workto the action of the stitch-forming mechanism, anelement operatin in the work-exposing aperture of one of said clamping means duringthe sewing, said one of said clamping means having a clearance opening leading from its work-exposmg aperture to permit the work-clamp and said element to be relatively shifted, said work-clamp also including an auxiliary. clamping element disposed 1n said opening 7 and displacea-ble from work-clamping position therein.

2. A sewing machine having, in combination, stitch-forming mechanism, a needlethroat member, ajwork-clamp including coacting upper and lower work-clamping" means, the lower Work-clamping means havmg a clearance opening for the needle-throatmember, means for relatively shifting the needle-throat member and work-clamp horizontally out of and into sewing relation, said work-clamp also including auxiliary lower work-clamping means disposed in said opening and displaceable from work-clamping position in said opening.

3. A sewing machine having, in combination, stitch-forming mechanism, a needlethroat member, a work-clamp including (50-.

acting upper and lower work-clamping means, the lower work-clamping means hav- 'ing a clearance opening for the needle-throat .member, means for relatively shifting the needle-throat member and work-clamp out ofand into sewing relation, said work-clamp also including auxiliary lower work-elamping means disposed in said opening, and

' automatic means for displacing said auxiliary L Work-clamping means from workclamping position in said opening when the needle-throat member and work-clamp are relatively shifted out of sewing relation.

4. A sewing-machine having, in combination, stitch-forming mechanism, a needlethroat member, a work-clamp including coacting upper and lower work-clamping means, the lower work-clamping means havingr a clearance opening for the needlethroat member, means for relatively shifting the needle-throat member and Workclamp out o and into sewing relation, said work-clamp also including auxiliary lower work-clamping means disposed in sald opening, and automatic means for displacing said auxiliary work-clamping means from workclamping position in said opening and for returning it to such work-clamping position when the needle-throat membertand workclamp are relatively shifted out of and restored to sewing relation.

5. A sewing machine of the buttonhole type haying, in combination, stitchforming 'mechamsm, a work-clamp having coacting upper and lower clamping means apertured to expose an area of the work to the action of the stitch-forming mechanism, a needle throat member disposed, when in sewing position, in the aperture of the lower clamping means, buttonhole cutting mechanism, means for relatively moving the work-clamp and needle-throat member out of sewing relation to expose the work to the action of the buttonhole cutting mechanism, said lower clamping means having a needle-throat clearance opening leading from said work-exposing aperture to permit'of said. relative movement, and auxiliary lower work-clamping means displaceably disposed in said opening.

6. A sewing machine of the buttonhole type having, in combination, stitch-forming mechanism, a work-clamp having coacting upper and lower clamping means apertureth to expose an area of the work to the action of the stitch-forming mechanism, a needlethroat member disposed when in sewing position in the aperture of the lowerclamping means, buttonhole cutting mechanism, means for relatively moving the work-clamp and needle-throat member out of sewing relation to expose the work to the action of the buttonhole cutting mechanism, said lower clamping means having a needle-throat clearance opening leading from said workexposing aperture to permitof said relative movement,- auxiliary lower work-clamping means displaceably disposed in said opening, and means actuated by the buttonhole cutting mechanism for displacing said lower auxiliary work-clamping means from work-clamping position in said opening.

7. A work-clamp for sewing machines having lower clamping plates and upper clamping feet apertured to expose an area of the work clamped between them, said lower clamping plates having an opening leading from the work-exposing aperture therein, and auxiliary lower work-clamping means disposed in said opening in cooperative relation with said upper clamping feet and shiftable relatively to said lower clamping plates out of such cooperative relation.

8. A work-clamp for sewing machines having lower clamping plates and u per clamping feet, the lower clampin p ates having a sewing aperture and a c earance opening leading from said aperture, and levers pivotally mounted on said clamping plates and having clamping portions ,disposed in said clearance opening in workclamping relation with said upper clamping feet, said levers being shiftable to displace said clamping portions from such workclamping relation.

9. A sewing machine of the buttonhole type having, in combination, stitch-forming mechanism, a work-clamp having coacting upper and lower clamping means apertured to expose an area of the work to the action of the stitch-forming mechanism, a needlethroat member disposed, when in sewing position, in the aperture of the lower clamping means, bnttonhole cutting mechanism, means for relatively moving the work-clamp and needle-throat member out of sewing relation to expose the work to the action of the but tonhole cutting mechanism, said lower clamping means having a needle-throat clearance opening leading from said workexposing aperture to permit of said relative movement, and auxiliary lower work-clamping means displaceably disposed in said opening, said auxiliary lower work-clamping means comprising a pair of spring-pressed levers having their work-clamping extremities disposed adjacent the needle-throat member and formed with inclined edge portions engageable by the needle-throat member for spreading such levers during the relative movement of the work-clam) and needle-throat member out of sewing relation.

In testimony whereof, I have signed my name to this specification.

/ EDWARD B. ALLEN. 

